2. The kinetic energy of a rocket is given by the formula E =-mv² , where E is in Joules, m is in kg and v is in m/s. If a rocket has a mass of 80 000 kg, is burning fuel (losing mass) at a rate of 90 kg/s, is travelling at 70 m/s and is accelerating at 9 m/s, what is the rate of change of energy (in Joules /s)? HINT: use the product rules

2. The kinetic energy of a rocket is given by the formula E =-mv² , where E is in Joules, m is in kg and v is in m/s. If a rocket has a mass of 80 000 kg, is burning fuel (losing mass) at a rate of 90 kg/s, is travelling at 70 m/s and is accelerating at 9 m/s, what is the rate of change of energy (in Joules /s)? HINT: use the product rules

Physics for Scientists and Engineers: Foundations and Connections

1st Edition

ISBN:9781133939146

Author:Katz, Debora M.

Publisher:Katz, Debora M.

Chapter10: Systems Of Particles And Conservation Of Momentum

Section: Chapter Questions

Problem 10PQ: The velocity of a 10-kg object is given by v=5t2i(7t+2t3)j, where if t is in seconds, then v will be...

See similar textbooks

Similar questions

CASE STUDY On planet Betatron, mass is measured in bloobits and length in bots. You are the Earth representative on the interplanetary commission for unit conversions and find that 1 kg = 0.23 bloobits and 1 m = 1.41 bots. Express the density of a raisin (2 103 kg/m3) in Betatron units.
Alpha decay is nuclear decay in which a helium nucleus is emitted. If the helium nucleus has a mass of 6.80×10-27kg and is given 5.00 Me V of kinetic energy, what is its velocity?
You are playing a game and you push a cart to give it in. speed. The cart starts at the bottom (zero) of a ramp and after reaching the top of the ramp, the cart travels across a horizontal track w/ friction. The mass of the cart is 44 x 10^-3 kg. The ramp is 56 cm high. The length is 70 cm. What can you infer of the intial speed in (m/s)
3. An object with a mass of 725kg sits 34m above the ground. What is its PE,? 4. An object with mass 23kg falls from 249m and hits the ground. What is its PE before it begins to fall? What is its PE when it hits the ground? 5. If an object has a mass of 35.7kg and its KE = 96375.9J, what velocity is it traveling at?
2. A mass of 4 kg is dropped with a velocity of 5 m/s. a. Find an expression for the velocity of an object if the force due to air resistance is 60v. b. Find the limiting velocity for the object.
Which description includes a scalar quantity? The elevator moved upwards at 2.5m/s. The box was moved to the left 3m. The car accelerated at 5m/s². O The desk had a mass of 47 kg. Which description includes a vector quantity? O They drove for 1 hour. The fish pulled with a force of 2 N. The dog had a mass of 14 kg. The speed of the boat was 15 m/s. Erin walked 2 meters to the north, 4 meters east, 3 meters to the south, and 1 meter east. Which of the following is true? Her distance traveled was 3 meters. Her displacement was 5.1 meters. Her distance traveled was 9 meters. Her displacement was 10 meters.
On a 119 meter high roller coaster is a 75 kg car at rest. Assuming there is no friction, what will its velocity be at the bottom? a) The car from the previous roller coaster begins its journey towards a second climb with a speed of 58 m / s. Assuming there is no friction, how high will it reach before stopping?
You push a 80-kg file cabinet to the right on a frictionless horizontal surface with a force of 175 N from rest, the cabinet moves a distance of 12 m. What is the final speed of the cabinet, in m/s? Your answer needs to have 2 significant figures, including the negative sign in your answer if needed. Do not include the positive sign if the answer is positive. No unit is needed in your answer, it is already given in the question statement.
A force F= (-2Nm)xi+(4Nm2)x2j-8Nk and a second force F=(-4Nm2)x2j-8Nk are applied to a 4 kg object between x= 1m and x= 6m. If the objects initial velocity is Vi=(-.9)i+(1.2)j+(.8)k m/s what is the objects's speed when it hits 6m?
a)Find an expression for the bullet's initial speed v_B in terms of m, M, k, and d. Express your answer in terms of the variables m M k d b)What was the speed of a 1.8 g bullet if the block's mass is 1.1 kg and if the spring, with k = 37 N/m , was compressed by 16 cm? Express your answer in meters per second. c)What percentage of the bullet's energy is "lost"? Express your answer in percent to four significant figures.
3. A block of mass m is connected to a spring of spring constant k and lies on a frictional road. The coefficient of friction between the road and the block is p. The spring is initially compressed by and the spring-mass system is released from rest. The block stops after a while. Find the distance traveled by the block in terms of m, k and X-Q JE 1
A.) Using the alternate form of Newton's second law, compute the force (in N) needed to accelerate a 1,170 kg car from 0 to 30 m/s in 20 s. The change in momentum is the car's momentum when traveling 30 m/s minus its momentum when going 0 m/s. (Enter the magnitude.) ________ N B.) A runner with a mass of 78 kg accelerates from 0 to 8 m/s in 4 s. Find the net force on the runner using the alternate form of Newton's second law.________ N